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Biomedical subjects

Y Shimada

Publications and source records attributed to Y Shimada.

At least 91 records · Page 5Linked to original sources

Phase I-II study of irinotecan combined with mitomycin-C in patients with advanced gastric cancer.

BACKGROUND: Irinotecan (CPT-11) shows synergism with mitomycin-C (MMC) in a preclinical setting. The goals of this study were to determine the maximum tolerated dose (MTD), the dose limiting toxicity, the recommended dose (RD), and preliminary anti-tumor activity in a combined CPT-11 and MMC treatment of advanced gastric cancer. PATIENTS AND METHODS: The study was designed to evaluate escalated doses of CPT-11 and MMC administered every two weeks. Five escalating dose levels were studied (CPT-11/ MMC: 100/5; 125/5; 150/5; 150/7; 150/10 mg/m2). RESULTS: Thirty-one patients were enrolled. Thirty patients were assessable for toxicity and tumor response for 89 treatment cycles. The median age was 60 years (32-73 years), and most patients (90%) had a performance status of 0 to 1. Fourteen patients were previously treated and 17 were chemotherapynaive. The MTD was CPT-11 150 mg/m2 plus MMC 10 mg/m2, in which all three patients experienced grade 4 neutropenia. including one episode of prolonged and one of febrile neutropenia, and one patient experienced grade 3 diarrhea during the first cycle. Fifteen partial responses were observed. CONCLUSIONS: The RD based on this phase I-II study was CPT-11 150 mg/m2 plus MMC 5 mg/m2 administered every two weeks. This combination demonstrates promising activity against advanced gastric cancer and warrants further investigation in another phase II study.

Adult↗

Lymph node micrometastasis and prognosis in patients with oesophageal squamous cell carcinoma.

BACKGROUND: The purpose of this study was to investigate whether the presence of lymph node micrometastasis in pathological lymph node-negative (pN0) oesophageal squamous cell carcinoma had prognostic value. METHODS: Some 1840 lymph nodes were obtained from 50 patients with pN0 oesophageal squamous cell carcinoma who underwent curative resection of the primary tumour with systematic lymphadenectomy. These lymph nodes were examined immunohistochemically with anticytokeratin antibody (AE1/AE3). Lymph node micrometastases newly detected by immunohistochemistry were classified as micrometastasis. Additionally, lymph node micrometastases were classified into three stages: stage 1, one individual AE1/AE3-positive cell; stage 2, multiple individual positive cells; stage 3, one or multiple positive clusters. RESULTS: Micrometastases were detected in 20 patients (40 per cent). A higher stage of micrometastasis was associated with greater pathological tumour (pT) size (P = 0.023). Recurrent tumours developed in nine patients. However, the frequency of recurrence was similar in patients with, or without, micrometastasis (five of 20 and four of 30 patients respectively; P = 0.25). Twenty-three of 30 patients without micrometastasis survived, whereas 15 of 20 patients with micrometastasis were still alive (5-year overall survival 75 and 78 percent respectively, P = 0.91). Twenty-six of 30 patients without micrometastasis had no recurrence, whereas 15 of 20 patients with micrometastasis had no recurrence (5-year relapse-free survival 86 and 73 per cent respectively, P = 0.37). There was no significant difference in prognosis with respect to the stages of micrometastasis. Multivariate analysis also showed that micrometastasis was not an independent prognostic factor (P = 0.73). CONCLUSION: Immunohistochemical detection of lymph node micrometastasis may be an indicator of lymphatic dissemination of tumour cells. However, the presence of micrometastasis had no impact on the prognosis of node-negative patients with oesophageal squamous cell carcinoma.

Aged↗

Elevated serum L-selectin levels and decreased L-selectin expression on CD8(+) lymphocytes in systemic sclerosis.

L-selectin is expressed on most circulating leucocytes and mediates leucocyte rolling on endothelium at sites of inflammation. Following rolling or activation of leucocytes, cell surface L-selectin is released as soluble L-selectin (sL-selectin). In the present study, we assessed serum levels of sL-selectin by ELISA and blood leucocyte L-selectin expression by flow cytometry in patients with systemic sclerosis (SSc). Serum levels of sL-selectin in patients with SSc (n = 51) were significantly higher than in normal controls (n = 30) while sL-selectin levels were similar for systemic lupus erythematosus patients (n = 20) and normal controls. Furthermore, SSc patients with elevated sL-selectin levels had inflammatory joint involvement, pitting scar/ulcers, and diffuse pigmentation more frequently than those with normal sL-selectin levels. The frequency of L-selectin(+) population among CD8(+) T cells was significantly decreased in SSc patients (n = 30) compared with normal controls (n = 20), while that among CD4(+) T cells, B cells, monocytes, and neutrophils was similar for SSc patients and normal controls. These suggest that elevated sL-selectin levels and decreased frequency of L-selectin+ CD8(+) T cells in SSc patients may be involved in inflammation associated with SSc.

Adolescent↗

Site-directed mutagenesis of human membrane-associated ganglioside sialidase: identification of amino-acid residues contributing to substrate specificity.

Unlike microbial sialidases, mammalian sialidases possess strict substrate specificity, for example the human membrane-associated sialidase, which hydrolyzes only gangliosides. To cast light on the molecular basis of this narrow substrate preference, predicted active site amino-acid residues of the human membrane sialidase were altered by site-directed mutagenesis. When compared with the active site amino-acid residues proposed for Salmonella typhimurium sialidase, only five out of 13 residues were found to be different to the human enzyme, these being located upstream of the putative transmembrane region. Alteration of seven residues, including these five, was followed by transient expression of the mutant enzymes in COS-1 cells and characterization of their kinetic properties using various substrates. Substitution of glutamic acid (at position 51) by aspartic acid and of arginine (at position 114) by glutamine or alanine resulted in retention of good catalytic efficiency toward ganglioside substrates, whereas other substitutions caused a marked reduction. The mutant enzyme E51D exhibited an increase in hydrolytic activity towards GM2 as well as sialyllactose (which are poor substrates for the wild-type) with change to a lower Km and a higher Vmax. R114Q demonstrated a substrate specificity shift in the same direction as E51D, whereas R114A enhanced the preference for gangliosides GD3 and GD1a that are effectively hydrolyzed by the wild-type. The inhibition experiments using 2-deoxy-2,3-didehydro-N-acetylneuraminic acid were consistent with the results in the alteration of substrate specificity. The findings suggest that putative active-site residues of the human membrane sialidase contribute to its substrate specificity.

Amino Acid Sequence↗

Cognitive function and frontal lobe atrophy in normal elderly adults: Implications for dementia not as aging-related disorders and the reserve hypothesis.

We examined the relations between cognitive function and age and education in the normal elderly population. As per the community-based stroke, dementia, and bed confinement prevention in the town of Tajiri, neuropsychological assessments, including the Cognitive Ability Screening Instrument (CASI), were performed for 99 randomly selected normal elderly subjects. We assessed the frontal function (working memory, word fluency, Trail-Making Tests, CASI subitems of list-generating fluency, attention, and concentration/mental manipulation), language function (proverbs, CASI subitem language), non-language function (the digit symbol test of the Wechsler Adult Intelligence Scale-Revised (WAIS-R), CASI subitem visual construction), memory (Alzheimer's Disease Assessment Scale recall/recognition, story recall, CASI subitems short and long-term memory, the Rey-Osterrieth Complex Figure Test), and the global function (CASI subitems orientation and abstraction and judgment). We found that the only test affected by age was the digit symbol test of the WAIS-R. The effects of education were distributed among various tests. There was a significant correlation between age and the frontal lobe atrophy in the lower educated group. The present findings suggest that cognitive function is spared by the aging process itself and dementia should be considered as age-related, not aging-related disorders, and that education might have a protective effect on cognitive change, supporting the reserve hypothesis.

Age Factors↗

Covered metallic stent treatment of a patient with spontaneous rupture of the esophagus.

A patient with a potentially fatal condition as a result of esophago-pneumo-broncho fistula was successfully treated with the insertion of a self-expanded covered metallic stent. Severe regurgitation resulted in the removal of the stent 3 months after insertion. Stricture after removal of the stent required pneumatic balloon dilation. The use of a self-expanded covered metallic stent is effective for the treatment of spontaneous esophageal rupture; however, early removal of the stent is recommended.

Bronchial Fistula↗

The effects of therapeutic electric stimulation on acute muscle atrophy in rats after spinal cord injury.

OBJECTIVE: To evaluate the effects of electric stimulation in preventing acute muscle atrophy after spinal cord transection in rats. DESIGN: A randomized experimental design. SETTING: Animal facilities for experimental medicine. ANIMALS: Fifty-six adult male Wistar rats assigned to control, low-frequency, and high-frequency groups. INTERVENTIONS: The rats were implanted with a percutaneous intramuscular electrode in the vicinity of the peroneal nerve; then the spinal cord was transected in a T9 level. The stimulation frequency was low (20Hz) or high (100Hz). The stimulation cycle was 4 seconds of stimulation every 8 seconds. MAIN OUTCOME MEASUREMENTS: The lesser fiber diameters from type 1, 2A, and 2B muscle fibers were measured. In another assessment, maximal contraction force was measured. The muscle force produced at 20 and 100Hz was expressed as increasing values in tetanic force. RESULTS: Comparison between nonstimulated and stimulated tibialis anterior muscles found that atrophy of type 1 fibers (p < .01) and type 2B fibers (p < .05) at both stimulated levels and of type 2A fibers at 100-Hz level (p < .05) was prevented by therapeutic electric stimulation (TES). There were significant differences in the size of muscle fiber diameter between nonstimulated and stimulated muscles at 100Hz in type 2A and, markedly, in type 2B. The increasing value of muscle force was significantly greater at 100Hz than at 20Hz (p < .05). No significant histologic differences were observed between high- and low-frequency stimulated fibers of any of the 3 muscle types. CONCLUSIONS: Acute atrophy of muscle fibers was more effectively prevented by high-frequency stimulation (100Hz) than by no stimulation or low-frequency stimulation (20Hz). The increasing value of muscle force was significantly greater at high-frequency than low-frequency stimulation, suggesting that the clinical application of high-frequency stimulation in acute spinal cord injury should be studied.

Acute Disease↗

CCR4 memory CD4+ T lymphocytes are increased in peripheral blood and lesional skin from patients with atopic dermatitis.

BACKGROUND: Recent studies have reported that TH1 and TH2 cells express CXCR3 and CCR4, respectively. OBJECTIVE: Our goal was to assess the association of CCR4 and CXCR3 expression with TH2 and TH1 cells and association of CCR4 and CXCR3 expression with inflammation in patients with atopic dermatitis (AD). METHODS: Intracellular cytokine production and chemokine receptor expression in blood T cells were examined by flow cytometry. Immunohistochemical expression of chemokine receptors was also investigated in chronically lesional skin. RESULTS: CCR4+ and CXCR3+ CD4+ T cells predominantly produced IL-4 and IFN-gamma, respectively. Although the frequency of CXCR3+ cells among CD4+ CD45RO+ T cells was similar for patients with AD (n = 29) and healthy control subjects (n = 19), patients with severe AD (n = 14) had a reduced frequency of CXCR3+ cells. In contrast, the frequency of CCR4+ cells and the CCR4/CXCR3 ratio were higher in patients with AD (n = 22) than healthy control subjects (n = 16) and correlated with disease severity of AD. The frequency of CCR4+ cells correlated positively with eosinophil numbers and serum IgE levels, whereas the frequency of CXCR3+ cells correlated inversely with eosinophil numbers. The frequency of CCR4+ or CXCR3+ cells was similar in patients with psoriasis (n = 6) and healthy control subjects. Immunohistochemical analysis showed that the frequency of CCR4+ cells among CD4+ T cells in chronically lesional skin of patients with AD (n = 9) was higher than that of patients with psoriasis (n = 4). CONCLUSION: Our data suggest the association of CCR4 expression with TH2 cells, the predominance of CCR4+ cells in blood from patients with AD, and an important role of CCR4 in the migration of TH2 cells from blood into AD lesional skin.

CD4-Positive T-Lymphocytes↗

Bonding amalgam to enamel: shear bond strength and SEM morphology.

STATEMENT OF PROBLEM: Most studies of amalgam bonding have used dentin as the substrate. There is little data on bonding to enamel. PURPOSE: This study evaluated the shear bond strength of amalgam to enamel with the use of 3 resin cements, 1 resin-modified glass ionomer lining cement, and 2 dentin bonding agents. MATERIAL AND METHODS: Sixty bovine teeth were trimmed to expose a flat enamel surface and randomly assigned to 6 test groups of 10 specimens each. A single-plane lap shear test assembly was used. The enamel surfaces were treated with either Amalgambond Plus (group I, control), 2 coats of Amalgambond Plus (group II), light-polymerized Panavia F followed by an additional coat of autopolymerized Panavia F (group III), light-polymerized Fuji Lining LC followed by an additional coat of acid-base set Fuji Lining LC (group IV), Clearfil SE Bond followed by an additional coat of autopolymerized Panavia F (group V), or Single Bond followed by an additional coat of autopolymerized RelyX ARC (group VI). Freshly mixed amalgam was condensed against the treated enamel surfaces. Shear bond strengths for each group were compared with 1-way ANOVA and post hoc Duncan's test (P=.05). Fracture modes were examined visually. SEM observations of the fractured enamel surfaces, interfacial morphology, and conditioned enamel surfaces for each group were performed. RESULTS: Low bond strengths of 1.2 and 1.6 MPa were obtained in groups VI and I, respectively. The dual application of materials in all remaining groups resulted in higher bond strengths that ranged from 14.2 to 15.7 MPa. SEM illustrations revealed various degrees of intermingling between the adhesive material and amalgam. The conditioned enamel surfaces were morphologically varied according to conditioning solution. CONCLUSION: In this in vitro study, with the exception of group VI, the dual application of either adhesive resins or resin-modified glass ionomer resulted in satisfactory bond strengths of amalgam to enamel (up to 16 MPa).

Acid Etching, Dental↗

Characteristic association between K-ras gene mutation with loss of heterozygosity in X-ray-induced thymic lymphomas of the B6C3F1 mouse.

PURPOSE: To elucidate the characteristics of radiation carcinogenesis, the spectra of K- and N-ras oncogene mutations, loss of heterozygosity (LOH) and their association in X-ray-induced thymic lymphomas (TL) were determined by comparing with those of N-ethyl-N-nitrosourea (ENU)-induced and spontaneously occurring TL. MATERIALS AND METHODS: TL that arose in untreated, X-ray-irradiated and ENU-treated B6C3F1 mice were examined both for K- and N-ras mutations by PCR-SSCP and DNA sequencing and for LOH by PCR with polymorphic microsatellite markers. RESULTS: (1) ras gene mutations were found in a proportion of TL from X-ray-exposed (approximately 20%) and ENU-treated (30-40%) mice while no ras gene mutations were found in spontaneous TL. N-ras mutations were rare. (2) The spectrum of ras gene mutations was diverse and seemed to differ little between X-ray-induced and ENU-induced TL, even though there was a higher frequency of ras mutations in ENU-induced TL that clustered to K-ras codon 12. (3) The X-ray-induced TL showing K-ras mutation were associated with LOH on chromosome 6, while those showing no K-ras mutation were associated with high frequency of LOH on chromosomes 4, 11 and 12. CONCLUSION: These results demonstrate that, in the B6C3F1 mouse TL, X-ray-induced lymphomagenesis showed both the co-expression, yet low occurrence of allelic imbalance on chromosome 6 and K-ras mutation, and exclusive expression of frequent allelic imbalance on chromosomes 4, 11 and 12 and K-ras mutation.

Animals↗

Gray matter of the bovine cervical spinal cord is mechanically more rigid and fragile than the white matter.

The gray matter of the cervical spinal cord has been thought to be equally or less rigid than the white matter. Based on this assumption, various studies have been conducted on the changes of stress distributions within the spinal cord under mechanical compression, although the mechanical properties of the white and gray matters had not been fully elucidated. The present study measured the mechanical properties of the white and gray matter of bovine spinal cords. For both the white and gray matter, the stress-strain curves had a nonlinear region, followed by a linear region, and then a region where the stresses plateaued before failure. In the nonlinear region, stress was not significantly different between the gray and white matter samples (strain approximately 0-10%), while stress and Young's modulus in the gray matter was significantly higher than the white matter in the linear part of the curve. The gray matter ruptured at lower strains than the white matter. These findings demonstrated the gray matter is more rigid and fragile than the white matter, and the conventional assumption (i.e., the white matter is more rigid than the gray matter) is not correct. We then applied our data to computer simulations using the finite element method, and confirmed that simulations agreed with actual magnetic resonance imaging findings of the spinal cord under compression. In future computer simulations, including finite element method using our data, changes in stress and strain within the cervical spinal cord under compression would be clarified in more detail, and our findings would also help to elucidate the area which can easily receive histologic damage or which could have hemodynamic disorders under mechanical compression, as well as severity and location of biochemical and molecular biological changes.

Animals↗

Suppression of N-nitrosomethylbenzylamine (NMBA)-induced esophageal tumorigenesis in F344 rats by JTE-522, a selective COX-2 inhibitor.

Recent studies have demonstrated that overexpression of cyclooxygenase-2 (COX-2) and elevation of COX-2-mediated synthesis of prostaglandin E(2) (PGE(2)) were observed in various cancers including esophageal cancer, but their roles in carcinogenesis of the esophagi still remain unclear. To address the issue, we observed the reduction of N:-nitrosomethylbenzylamine (NMBA)-induced tumorigenesis in rat esophagi via JTE-522 (4-[4-cyclohexyl-2-methyloxazol-5-yl]-2-fluorobenzenesulfonamide), a selective COX-2 inhibitor. In this study, 54 F344 male rats were divided into nine groups; JTE-522 (3, 9 and 30 mg/kg) was administered orally. We also examined the effects of JTE-522 on COX-2 mRNA and synthesis of PGE(2). In the group in which JTE-522 was administered intermittently at a daily dose of 30 mg/kg, the number of NMBA-induced esophageal tumors per rat significantly reduced, to 62% (P< 0.05), but the size of the tumors was not significantly inhibited. In the group in which JTE-522 was administered continuously five times weekly for 24 weeks at a daily dose of 9 mg/kg, both the number and size of tumors significantly reduced, to 29 and 44%, respectively (P<0.05). Furthermore, JTE-522 suppressed not only tumor formation but also developing carcinomas (P<0.0021) [corrected]. In this study, treatment with NMBA alone resulted in an approximately 5-fold rise in expression of COX-2 mRNA detected by semi-quantitative RT-PCR analysis and an approximately 7-fold increase in the production of PGE(2) measured by ELISA compared with the normal esophageal mucosa. The up-regulated COX-2 expression did not decrease with the treatment of JTE-522 at the 3, 9 and 30 mg/kg doses; however, the increased levels of PGE(2) synthesis were significantly decreased by administering JTE-522 (P<0.01). Our study suggests that COX-2-mediated PGE(2) is important in NMBA-induced esophageal tumorigenesis in rats, and therefore may be a promising chemotherapeutic target for the prevention and treatment of esophageal cancer, especially with selective COX-2 inhibitors.

Animals↗

A novel alpha-amino-acid esterase from Bacillus mycoides capable of forming peptides of DD- and DL-configurations.

A novel alpha-amino-acid esterase possessing some properties favorable for the synthesis of D-amino acid-containing peptides has been purified from the culture broth of Bacillus mycoides. The enzyme consisted of 4 subunits of 39 kDa, had an isoelectric point of 7.0, and showed its maximum activity at around 47 degrees C and pH 7.6. The enzyme activity was strongly depressed by phenylmethanesulfonyl fluoride, but not by penicillin G or ampicillin, suggesting that the protein is a serine enzyme lacking penicillin-binding ability. The enzyme hydrolyzed a variety of D- and L-amino acid methyl esters with concomitant formation of homooligomers from D-Phe, D-Trp, D-Tyr, and D-Asp(OCH(3)) methyl esters, but it did not act on the D- or L-amino acid amides tested. Incubation of a mixture of Ac-D-Phe-OMe and D-/L-Leu-NH(2) with the enzyme yielded Ac-D-Phe-D-/L-Leu-NH(2) together with Ac-D-Phe-OH, the hydrolysate of the carboxyl component. To its credit, the enzyme failed to hydrolyze casein as well as peptides including diastereomers of diphenylalanine and dialanine, indicating that the enzyme would not cause secondary hydrolysis of once-formed peptides. These observations indicate the potential utility of the newly isolated enzyme for the synthesis of D-amino acid-containing peptides.

Bacillus↗

Role of central nervous system nitric oxide in the development of neurogenic pulmonary edema in rats.

OBJECTIVE: The present study was undertaken to evaluate roles of nitric oxide in the central nervous system in the development of neurogenic pulmonary edema. Nitric oxide donor compounds have been reported to be effective for controlling some kinds of pulmonary edema. DESIGN: Randomized trial. SETTING: Experimental university pharmacology laboratory. SUBJECTS: Wistar rats anesthetized with pentobarbital. INTERVENTIONS: Neurogenic pulmonary edema was induced by injections of fibrinogen and thrombin into the cisterna magna. Physiologic roles of nitric oxide were evaluated by using NG-nitro-l-arginine methyl ester (a nitric oxide synthase inhibitor) or l-arginine (a nitric oxide donor compound). Vagus nerves were either left intact or bilaterally severed 20 mins before the injections of fibrinogen and thrombin. MEASUREMENTS AND MAIN RESULTS: Because enhanced sympathetic nerve activity mediates neurogenic pulmonary edema, the concentration of neuropeptide Y, a neurotransmitter, in edema fluid was measured by using enzyme-linked immunosorbent assay. To evaluate the severity of pulmonary edema and pulmonary vascular permeability, lung water content and protein concentration in edema fluid were analyzed. In rats with intact vagus nerves, injection of NG-nitro-l-arginine methyl ester into the cisterna magna worsened the pulmonary edema, whereas l-arginine had no effect. In contrast, in vagotomized rats, l-arginine abrogated pulmonary edema, whereas NG-nitro-l-arginine methyl ester exerted no influence. Likewise, the ratio of edema fluid protein to serum protein and the neuropeptide Y concentration were increased by NG-nitro-l-arginine methyl ester in rats with the vagus nerves intact and were diminished by l-arginine in vagotomized rats. CONCLUSIONS: Neurogenic pulmonary edema is characterized by elevated pulmonary vascular permeability and may be inhibited by nitric oxide production in the medulla oblongata.

Analysis of Variance↗

Brassinosteroid-6-oxidases from Arabidopsis and tomato catalyze multiple C-6 oxidations in brassinosteroid biosynthesis.

Brassinosteroids (BRs) are steroidal plant hormones that are essential for growth and development. It has been proposed that BRs are synthesized via two parallel pathways, the early and late C-6 oxidation pathways according to the C-6 oxidation status. The tomato (Lycopersicon esculentum) Dwarf gene encodes a cytochrome P450 that has been shown to catalyze the C-6 oxidation of 6-deoxocastasterone to castasterone. We isolated an Arabidopsis ortholog (AtBR6ox gene) of the tomato Dwarf gene. The encoded polypeptide has characteristics of P450s and is classified into the CYP85 family. The AtBR6ox and tomato Dwarf gene were expressed in yeast and the ability of the transformed yeast cells to metabolize 6-deoxo-BRs was tested. Metabolites were analyzed by gas chromatography-mass spectrometry. Both enzymes catalyze multiple steps in BR biosynthesis: 6-deoxoteasterone to teasterone, 3-dehydro-6-deoxoteasterone to 3-dehydroteasterone, 6-deoxotyphasterol to typhasterol, and 6-deoxocastasterone to castasterone. Our results indicate that the AtBR6ox gene and the tomato Dwarf gene encode steroid-6-oxidases and that these enzymes have a broad substrate specificity. This suggests that the BR biosynthetic pathway consists of a metabolic grid rather than two separate parallel pathways.

Amino Acid Sequence↗

A novel amplicon at 9p23 - 24 in squamous cell carcinoma of the esophagus that lies proximal to GASC1 and harbors NFIB.

The non-random amplification of DNA at 9p23 - 24 observed in various types of human cancers, including esophageal squamous cell carcinomas (ESCs), may reflect the locations of important tumor-associated genes. Our previous studies using ESC cell lines defined an amplicon in this region and identified a novel gene, GASC1, as a target of the amplification. Since different regions within the same chromosome arm are often involved in amplification in a syntenic or non-syntenic manner, we characterized the amplicon at 9p23 - 24 in 35 ESC cell lines (29 KYSE series and 6 YES series), and examined possible involvement of non-syntenic amplifications at 9p23 - 24 in 32 primary ESCs. Our results clearly indicated that two target regions for DNA amplification exist at 9p23 - 24; the major amplicon contains GASC1, and the minor one harbors a transcription factor, NFIB, centromeric to the GASC1 locus.

Blotting, Southern↗